Method of producing hollow propeller blade constructions



J. H. McKEE Nov. 18, 1947.

METHOD OF PRODUCING HOLLOW PROPELLER BLADE CONSTRUCTIONS Filed Sept. 3,1943 2 Sheets-Sheet 1 INVEN TOR. 7amesEMcKe Nov. 18, 1947. J. H. McKEE2,431,064

METHOD OF PRODUCING HOLLOW PROPELLER BLADE CONSTRUCTIONS Filed Sept. 3,1943 2 Sheets-Sheet 2 m k b Q i t INVENTOR. .famearH .416. K26

ATTO/f/VEK Patented Nov. 18, 1947 METHOD or PRODUCING noL'Low PRO-PELLER BLADE consranc'rrons James H. McKee, North Caldwell, N. J.,assignor to Curtiss-Wright Corporation, a corporation of DelawareApplication September 3, 1943, Serial No. 501,192

ration to thereby provide an own channel for the insertion between saidplates of a welding electrode or equivalent means for securing saidmemher in reinforcing position.

Various other objects, advantages and features of my invention willbecome apparent from the following detailed description.

My invention resides in the propeller plate, reinforced propeller blade,novel methods, constructions and arrangements of the characterhereinafter described and claimed.

For an understanding of my invention, reference is to be had to theaccompanying drawings.

in which:

Fig. 1 is a plan view showing a camber propeller plate;

Fig. 2 is a longitudinal, vertical sectional view showing a thrustpropeller plate;

Fig. 3 is a longitudinal, vertical sectional view showing the camberpropeller plate of Fig. 1 and an attached connecting member;

Fig. 4 is a transverse, vertical sectional view illustrative of apropeller plate while subjected to a shaping operation;

Figs. 5 and 6 are transverse vertical sectional views illustrative of awelding operation per- 6 Claims. (Cl. 29-1563) enerally is of ellipticalconfiguration in correspondence with the aforesaid shallow opening ofthe camber plate C and, to less extent than the latter, it has convexshape. As will be noted from Fi 2, said thrust plate 1'' does notcomprise a shank section as does the camber plate C.

As illustrated, the plates C and T comprise the respectivelongitudinally extending integral ribs 1- and TI which, when said platesare assembled, are disposed substantially in facing relation or in acommon plane. In the form of the invention herein shown, although notnecessarily, the ribs 1" formed on a blade construction or a partiallycompleted propeller blade;

Fig. 7 is a transverse, vertical sectional view illustrating a step inthe production of the hollow propeller blade of my invention; and

Figs. 8 and 9 are transverse, vertical sectional views illustrative ofthe complete propeller blade.

Referring to Figs. 1 and 2, I have shown a metallic camber plate C and ametallic thrust plate T of the general character known in the art forforming a hollow propeller blade B as shown in Figs. 8 and 9.

As illustrated, the camber plate C comprises a tubular shank l. havingextending therefrom the plate proper 2 which generally is of convexconfiguration, the convexity decreasing in a progressive manner as thetip of the plate is approached whereby said camber plate C defines ashallow opening of generally elliptical configuration. The thrust plate'1 comprises a plate properia which and Ti are formed, as described inmy pending application, Serial No. 493,314, filed July 2, 1943; bysubjecting uniformly thick plane sheets of metal, which form the blankplates for the respective camber and thrust plates C and '1 hereindisclosed, to two or more milling operations whereby each sheet of metalis longitudinally tapered in such manner that the thickness of eachsheet'of metal decreases longitudinally therealong toward the tip of theblade. The milling cutter is so shaped or arranged that, while thetaperin operation proceeds, a longitudinal strip'of the original sheetof metal remains intact, this strip of metal forming the aforesaid rib1' or H, the ends thereof toward the left terminating approximately atthe respective locations a, Figs. 1, 2, and 3. As a result of thedescribed milling operations, the thickness 0; height of each of theribs r and H increases progressively in a direction extendinglongitudinally along the propeller blade toward the tip thereof.Further, it is desirable that the milling cutter be so shaped that thedescribed operation causes each of the ribs r or rl to be bordered byfillets J as illustrated.

After the blank plates have been milled as described above, the camberplate C and the thrust plate '1' are broughttothe finished form hereindisclosed in Figs. 1, 2, and 3, by subjecting each of the partiallycompleted propeller plates having the integral longitudinal ribs,respectively, to suitable milling, trimming and shaping operations, theconvex configuration and the twist being imparted to the plate duringthe operation last noted, all as generally referred to in said pendingapplication, Serial No. 493,314, filed July 2, 1943. Thereafter, theaforesaid shallow opening of the camber plate C is closed by the thrustplate '1 when the two plates are secured together by weld metal 3 asshown in Figs. 8 and 9, to form the propeller blade.

As more fully disclosed in my pending application, Serial No. 496,232,filed July 26, 1943, granted August 2'7, 1946, No. 2,406,471, aconnecting or reinforcing metallic member or section of metal M ofsuitable tapered configuration is suitably held on the plate rib rthroughout a distance d thereof, Fig. 3. While said connecting member Mis thus held, it is secured to said rib r in any suitner, as, forexample, by metallic arc, resistance or atomic hydrogen welding. By thisoperation, the structure shown in Fig. 3 is produced.

In accordance with the invention, the finished thrust plate T of thecharacter referred to above is subjected to a reverse shaping operationprior to the time that it is assembled with the camber plate to form thecomplete blade. Thus, as shown in Fig. 4, I provide relatively movabledie members MI and M2 having a length the same as or less than that ofthe thrust plate T, the die MI being provided with a longitudinallyextending groove gl for the reception of the rib rl. With the diemembers MI and M2 open, the finished thrust plate T is properlypositioned between them whereupon, by closing said die members MI andM2, the thrust plate T is given the reverse configuration shown in. Fig.4.

After completion of the foregoing operation, the thrust plate T isassembled in proper relation with the camber plate and connecting memberstructure shown in Fig. 3 to thereby produce a propeller bladearrangement as shown in Figs. 5 and 6. As indicated in Fig. 2, the ribrl terminates short of the tip of the plate T a distance dl and, asindicated in Fig. 3, the rib r terminates short of the tip of the plateC a distance d2. Further, as will be understood from the aforesaidPatent No. 2,406,471, the ribs r and TI are suitably trimmed throughouta distance d3 so that, when the two plates T and C are properlyassembled, facing surfaces of said ribs engage or closely approach eachother throughout said distance (13. Further, when said plates areproperly assembled, the upper surface of the connecting member M eitherengages or closely approaches the lower surface of the rib rl of thethrust plate T throughout the distance d, Fig, 3.

By suitable means, not shown, the plate T is held in proper assembledrelation with respect to the plate C and the attached connecting memberM whereupon, in accordance with the invention, the facing surfaces ofthe ribs r and T! are secured together throughout the distance d3, Figs.2 and 3, and the facing surfaces of the connecting member M and the ribr are secured together throughout the distance d, Fig. 3.

In the form of the invention herein illustrated, although notnecessarily, there is utilized for the purpose aforesaid, an electrode eof suitable metallic arc welding apparatus. By reason of the fact thatthe thrust plate 'I' was reversely set as described above, a passage orchannel exists extending lengthwise of the propeller blade 50 that theelectrode e may be readily positioned in operative relation to the twosets of facing surfaces last described to produce a welded joint n02throughout a distance d3 between said facing surfaces of the ribs 1' andTI and a welded joint w3 throughout a distance d between said facingsurfaces of the connecting member M and the rib r. Further, by reason ofthe reverse configuration imparted to the thrust plate T, it becomespractical to introduce suitable filing or scraping tools interiorly ofthe hollow propeller blade in order to clean the welded joints w2 andw3.

By the operations described above, a short section of the thrust platerib rl is secured directly to the camber plate rib r, the remainder ofthe thrust plate rib rl being secured directly to the facing surface ofthe connecting member M to thereby produce the blade constructionillustrated in Figs. 5 and 6.

After completion of the foregoing, multi-section welding mandrels m asknown in the art are positioned within the hollow blade construction ateach side of the reinforcing arrangement comprising the connectingmembe'rM. Thereupon, an adjustable platen, h forming a part of a specialtable type welding jig or fixture, is operatively associated with theblade construction and mandrel structure, said adjustable platen itbeing lowered to exert pressure thereon to restore the thrust plate T toits original or finished configuration as shown in Fig. 7 and to hold itin such configuration. Thereafter, the weld metal sections 3 aredeposited in known manner to positively weld the thrust and camberplates T and C to each other at their leading and trailing edges. Thisresults in the production of the complete propeller blade illustrated inFigs. 8 and 9.

As stated, the die members MI and M2 may have a length the same as thethrust plate T. Alternatively, said die members MI. and M2 may besubstantially shorter than said thrust plate T and utilizable forreversely shaping the latter only throughout the thicker sectionthereof.

The blade reinforcement comprising the rib r and H together with theconnecting member M increases the stiffness of the propeller plates withresultant decrease in the amplitude of plate vibration or deflectionwhich may be excited aerodynamically or by engine pulsations. As aresult, stresses within the plates are reduced. Further, such increasein stiffness of th propeller plates raises the natural frequency thereofabove the range of objection-able frequencies to some extent at leastand this decreases the amplitude of plate vibration or deflection.

With respect to a propeller blade wherein the interior chamber issealed, deformation of the airfoil surface may arise due to thedifference of aerostatic pressures exteriorly and interiorly of theblade, this being caused (1) by pressure differences resulting fromchanges in altitude and (2) by pressure differences due to centrifugalaction on the air in the interior blade chamber. The aforesaid bladereinforcement comprising the ribs 1' and TI together with the connectingmember M decreases this deformation of the airfoil surface.

Within the purview of the invention, it shall be understood that thesection of the thrust plate T at the right of the rib rl, Fig. 5, mayretain its finished configuration while the section of said thrust plateTat the left, Fig. 5, is reversely bent as and for the purposedescribed. This follows because, if desired, only one side section ofsaid thrust plate T need be given the aforesaid reverse configurationfor the purpose of providing an open channel through which a weldingelectrode or equivalent may be introduced for the purpose stated. Byreverse configuration, I mean any configuration which is imparted tothecompleted thrust plate T, which changes it from its completed state forthe purpose stated. Obvi, ously, the dies MI and M2 may have variousconfigurations which need not be necessarily arcuate as illustrated.

While the invention has been described with respect to a certainparticular preferred example which gives satisfactory results, it willbe understood by those skilled in the art after understanding theinvention, that various changes and modifications may be made withoutdeparting from the spirit and scope of the invention and it is intendedtherefore in the appended claims to cover all such changes andmodifications.

What is claimed as new and desired to be secured by Letters Patent is:

1. In the art of producing a hollow blade construction, comprisingribbed convex plates, the steps which consist in shaping one of saidribcarrying propellerplates in part at least reversely as regards theexterior convex configuration thereof, assembling said plate with theother rib carrying propeller plate with the rib thereof facing a spacingmember welded to and project ing from the rib on said other platewhereby, due to the reverse configuration of said first named plate, anopen longitudinally extending channel is formed at the respective edgesof the blade construction, and inserting a welding electrode into saidchannel and between said plates to form a welded joint between saidfirst named rib and said spacing member.

2. In the art of producing a hollow blade construction, comprisingribbed convex plates the steps which consist in shaping one of saidribcarrying propeller plates in part at least reversely as regards theexterior convex configuration thereof, assembling said plate with theother rib carrying propeller plate with the rib of said reversed platefacing a longitudinally tapered spacing member welded to and projectingfrom the rib formed on said last named plate whereby, due to the reverseconfiguration of said first named plate, an open longitudinallyextending channel is formed at the respective edges of the bladeconstruction, and inserting a welding electrode into said channel andbetween said plates to form a welded joint between said first named riband said spacing member, shaping said first named plate to restore it toits original convex configuration, and welding said plates together atthe marginal edges thereof to form the blade construction.

3. In the art of producing a hollow propeller blade comprising ribbedconvex plates, the steps which consist in shaping one of saidrib-carrying propeller plates so that it has approximately reverseconcave-convex configuration as regards the exterior convexconfiguration thereof, -disposing said plate generally in blade-formingrelation with the other rib carrying propeller plate and with the ribthereof facing a longitudinally tapered spacing member welded to andprojecting from the rib formed on said last named plate whereby, due tothe reverse configuration of said first named plate, an openlongitudinally extending channel is formed at the respective edges ofsaid plates, inserting a welding electrode into welded Joint betweensaid first named rib and said spacing member, inserting a pair ofcomplementary sectional mandrels between said plates one on each side ofsaid spacing memben'shaping said first named plate to restore it to itsoriginal convex configuration, and welding said plates together at themarginal edges thereof to form the propeller blade.

4. In the art of producing a hollow blade construction comprising ribbedconvex plates at least one of said ribs being so extended as toconstitute at least in part a plate spacing means when Joined with theother rib, the steps which consist all) in shaping one of said ribcarrying propeller plates in part at least reversely as regards theexterior convex configuration thereof, assembling said plate with theother rib carrying propeller plate with the rib thereof facing andabutting the rib on said first named plate whereby, due to the reverseconfiguration of said first named plate, an open longitudinallyextending channel is formed at the respective edges of the bladeconstruction and inserting a welding electrode into said channel andbetween said plates to form a welded joint between said ribs.

5. In the art of producin a hollow blade construction comprising ribbedconvex plates at least one of said ribs being so extended as toconstitute at least in part a plate spacing means when Joined with theother rib, the steps which consist in shaping one of said rib carryingpropeller plates in part at least reversely as regards the exteriorconvex configuration thereof, assembling said "plate with the other ribcarrying propeller plate with the rib thereof facing and abutting therib on said first named plate, whereby, due to the reverse configurationof said first named plate, an open longitudinally extending channel isformed at the respective edges of the blade construction, inserting awelding electrode into said channel and between said plates to form awelded joint said plate with the other rib carrying propeller saidchannel and between said plates to form a plate with the rib thereoffacing and abutting the rib on said first named plate, whereby, due tothe reverse configuration of said first named plate. an openlongitudinally extending channel is formed at the respective edges ofthe blade construction and inserting a welding electrode into saidchannel and between said plates toiorm a welded joint between said rib,inserting an abrading tool'into said channel and between said plates toclean the welded joint, and thereafter reshaping said first named plateconvex to close the open longitudinally extending channel preparatory tocompleting said blade.

JAMES H. MCKEE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

